Fig. 4. The copy numbers of Lymnaea CREB2 and CREB1 mRNAs in single cerebral giant cells. (A) Amplification plots generated by an increase of reporter dye fluorescence with each cycle of PCR of Lymnaea CREB2 cDNA. The filled squares show standard solutions, and the open squares show the test samples. All reactions were performed in duplicate (6 µl each, which was 6/15 of the total volume of the reverse-transcribed products). An arbitrary threshold cycle was obtained in the exponential phase of PCR. (B) Standard curve for the starting quantity of Lymnaea CREB2 RNA. The filled circles show standard solutions, and the open circles the test samples. The estimated copy number of Lymnaea CREB2 mRNA in a single cerebral giant cell was between 30 and 240. (C) Amplification plots generated by an increase of reporter dye fluorescence with each cycle of PCR of Lymnaea CREB1 cDNA. The notation is the same as (A). (D) Standard curve for the starting quantity of Lymnaea CREB1 RNA. The notation is the same as (B). The estimated copy number of Lymnaea CREB1 mRNA in a single cerebral giant cell was below the determination sensitivity.